Code No. P0038: Oxygen Sensor (rear) Heater Circuit High Input




OPERATION




FUNCTION




TROUBLE JUDGEMENT


Check Conditions
Judgement Criterion

FAIL-SAFE AND BACKUP FUNCTION




PROBABLE CAUSES




DIAGNOSIS PROCEDURE


STEP 1. Perform resistance measurement at oxygen sensor (rear) connector.



  • Oxygen sensor (rear) connector check.
  • Disconnect connector, and measure at sensor side.
  • Resistance between terminal power supply line and engine-ECU OHRL line.
OK: 4.5 - 8.0 Ω (at 20°C)

Q. Is the check result normal?

Go to Step 2.
Repair or replace the connector, or replace the oxygen sensor (rear).

STEP 2. Check harness between engine control relay connector terminal and oxygen sensor (rear) connector terminal.



  • Check power supply line for short circuit.

Q. Is the check result normal?

Go to Step 3.
Repair or replace the connector, or repair the damaged harness wire.

STEP 3. Check harness between oxygen sensor (rear) connector terminal and engine-ECU connector terminal OHRL.



  • Check earthing line for short circuit.

Q. Is the check result normal?

Go to Step 4.
Repair or replace the connector, or repair the damaged harness wire.

STEP 4. M.U.T.-III diagnosis code



  • Reconfirmation of diagnosis code.

Q. Is diagnosis code stored?

Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).